4.7L Jumping Time
 

Had a timing arm break and put a new timing chain and tensioner set in. Cranked it up and it ran good but shut off when I put it in reverse and speedometer went to 120 and stuck. Ran like timining was off when I recranked it (will not run without me giving gas). Pulled it down and right sprocket was 1 tooth off. Reset timing rotated engine and put back together. Cranked it up and it idled good, hit reverse and it cut off. Cranked it and had to hold pedal to floor, motor run like timing was off again. Do you have to put oil pressure on the engine to pressurize the tensioners before you button it up? Why is it jumping time only after I put car in gear to move it? 3 months in my shop is too long for me to warrant keeping the pos. The timing chain was $900 from my local auto parts place. I can get $300 from the junkyard, should I tear it down again or haul it off and forget dodge, go chevy?

chevy, built like a rock, sinks like one too

honestly i doubt it skipped time again, and putting it in gear wouldnt be the cause of it, once its set it should stay set unless you have a bad tooth on the gear but i would expect that to be pretty obvious.

when you start the truck up, does it idle ok? or does it idle erratically? if it idles poorly check the battery, if the battery is weak it wont idle right, when you shift into gear it puts a load onto the engine and could easily effect it with a weak battery.

also iirc the 4.7 is an interference engine, that means if timing jumps you likely damaged a piston or valve.

+1 shrps, sounds like the battery.
Just don't go ford :D

Battery is new. It jumped on start up initially. When the arm broke the chain came off the sprocket so all the valves snapped shut. It runs now but very erratic. Engine jumps like it's out of balance, and shuts off when you let off the gas. Had 2 buddies listen to it and all three of us agree on the timing issue. And by the way this is my wife's, my 1991 Chevy has 285,000 moles on it and no problems.

*miles.

if i were you (convinced that its a timing issue) id open it up and check the timing if you are so certain thats what it is, but i have never seen these engines jump time without breaking a tooth off the gear or damaged chain, when you put it on i believe you are supposed to rotate the engine twice to make sure the timing marks still line up correctly.

however other things that contribute to not running w/o your foot on the gas are weak battery (idc if its new, at the very least get it load tested, its FREE!!!!!!!!) a bad IAC motor will choke the engine out, a bad TPS will screw with the readings to the computer.

also check that all the sensors going into the top of the engine are in good and the connections are tight.

Will check. I did rotate engine 2x by hand. Will go over the connections and have IAC checked out. I am not getting a check engine light and code reader is saying all is fine. Thanks.

personally i would rotate it more time then that by hand to make sure it was all correct, but then im alot OCD when it comes to working on my truck

+1 on the ocd part

Did you torque the center bolt for the idler gear? Because if you didn't that will give you all kind of problems.

Ok pulled the IAC and cleaned still ran the same. Had to hold it at 2k rpm to stay running. I pulled the connector off the IAC and still the same. Pulled the TPS sensor connector and it cranked up and ran fine idled at 500 rpm. Speedo is still sitting at 120 mph. Will replace TPS and see how it goes.

Could the transmission output sensor cause any idle problems? This could also cause my speedo malfunction.

transmisison output sensor could be speedo issue, but not the idle

Cleaned the TB, replaced the IAC, TPS. Checked all vacuum connections and load tested battery. Cranks and idles at 600 rpm cold, 700 hot. Test drove all ok until I hit the brakes, then it stalled. Had to hold gas to floor to crank. Then it idles at 300 a few minutes and comes back up to 700. Then all ok until I brake again. No check engine light. Any ideas?

Maybe a vacuum issue. Replace the check valve on the brake booster including the grommet. You need to get it from a dealer.

Also reset the PCM.

Nope! Checked for vacuum leaks with starter fluid. Replaced check valve. At idle in park and neutral all ok. Even with brake pedal in. Drive it down road, press brake to slow or stop it cuts off, no matter the speed. Calling a junkyard today to see what scrap metal price is. Gonna find something else. Been under the hood of this thing since March. Sick of fooling with it.

I know it can happen, my last one went out in reverse, this is my third one in this truck, I've used cloyes twice now and I am going with sealmaster this time!

I know that I'm way to late, but this may be of use to others searching for a fix to this problem!
When in doubt, run a compression test, if one whole bank is different than the other, then that is the side that either jumped time or damage to all valves!
Don't make the mistake that it can't jump time, it can jump one tooth and still run very rough and not do any damage to the valves or pistons.
I know I've got a lemon, but she rides nice!!!